In Long-Term Evolution (LTE) wireless communication systems as currently specified by the 3rd-Generation Partnership Project (3GPP), mobile terminals (“UEs”, in 3GPP parlance) can be in idle or connected mode. In idle mode, a UE has no connection to the base station (“evolved Node B”, or “eNB”, in 3GPP parlance). UEs in idle state thus have no possibility for user data transmission. Since UEs in idle mode consume less network resources tha UEs in connected mode, the network will switch UEs to idle state after a certain time of inactivity. Consequently, a fast transition from the idle mode to connected mode is a vital component of the system latency. In LTE standardisation, a target has been set up to reduce the random access set up time to less than 50 milliseconds.
The possibility to send the so called Non Access Stratum (NAS) Service Request together with the Radio Resource Control (RCR) Connection Request has been discussed at standardization meetings related to Release 8 of the 3GPP standards (see 3GPP R2-092080, “LTE Advanced Latency Performance”). By transmitting the NAS Service Request together with the RRC Connection Request, an eNB 110 could forward the NAS Service Request to the core network in an S1 connection setup at an earlier point in time, e.g. in parallel with the RRC Connection Setup, thereby reducing the overall time required for the transition procedure of a UE 105 from idle mode to connected mode.